1. Field of the Invention
The invention relates generally to the fire suppression and extinguishment field, and more specifically to a new and improved fire sprinkler in the fire suppression and extinguishment field.
2. Description of Related Art
Fire sprinkler systems have been used in the United States to protect warehouses and factories for over one hundred years. In a fire sprinkler system, a fire sprinkler is positioned near the ceiling of a room where hot “ceiling jets” spread radially outward from a fire plume. When the temperature at an individual sprinkler reaches a pre-determined value, a thermally responsive element in the sprinkler activates and permits the flow of water as a water jet through a duct toward a deflector. The deflector redirects the water jet into thin streams or “ligaments” that break up into droplets due to surface tension. The water droplets serve three purposes: (1) delivering water to the burning material and reducing the combustion rate, (2) wetting the surrounding material and reducing the flame spread rate, and (3) cooling the surrounding air through evaporation and displacing air with inert water vapor.
When fire sprinklers are located close to each other, the risk of “cold soldering” becomes a concern. Cold soldering occurs when a first fire sprinkler disperses a fire suppressing or extinguishing substance that directly cools a second fire sprinkler and prevents the second fire sprinkler from properly responding and activating. Thus, there is a need in the fire suppression and extinguishment field to create an improved fire sprinkler that reduces or eliminates the risk of cold soldering.
Furthermore, where fire suppressing systems and fire sprinkler components are evaluated in a scientific setting, fire control has been proven to be most effective by maximizing the following system variables: water discharge velocity, k-factor and water droplet size. Fire control is typically improved by: larger diameter supply lines, more (closely-spaced) supply lines, greater water velocity, higher k-factor and/or larger water droplet size. However, addressing these factors has been limited by the constraint of available supply line. Simply designing a prior art spray head so that it is capable of discharging at a greater velocity, or that possesses a higher k-factor, or produces larger droplet sizes is not an option because each increased aspect will require higher supply line pressure and/or larger diameter supply line piping—both of which substantially increase the cost of an installed fire suppression system.
Warehouse settings are a common application of fire suppressing systems with fire sprinkler components. In a warehouse, storage items—often palletized—are frequently stacked or arranged in long rows. Storage items usually represent a significant capital investment in either raw, partially finished or finished good/inventory. An unchecked fire can quickly destroy storage items either by direct combustion, or collaterally be heat, smoke or water. Furthermore, storage items stacked or arranged in long rows often offer an abundant fuel source for a fire to grow and quickly propagate, making it that much more difficult to extinguish the fire. It is therefore of great economic importance to rapidly contain fires detected in warehoused storage items. Fire containment is largely dependent on the delivery of large quantities of rapidly moving water streams composed of relatively large size water droplets. That is to say, early stage fire containment in a warehouse storage setting is maximized when a lot of high velocity water (or other fire suppressing liquid) is sprayed onto the fire source, and the water droplets are as large as possible.
This objective is often frustrated in warehouse storage settings due to the fact that stacked or arranged rows of storage items tend to make it difficult for the water spray to reach an interior fire. When storage items are stacked or arranged in rows, narrow gaps between adjacent storage items are formed. These marrow gaps are often characterized as flues. There are transverse flues and longitudinal flus. Transverse flues are formed in the gaps between adjacent storage items in the same row, whereas longitudinal flues are created in the gap between two adjacent rows when arranged back-to-back. When a fire originates between two rows of storage items, particularly when they are arranged back-to-back (i.e., with a longitudinal flue in between), it is very difficult to reach the fire with water dispersed from a fire sprinkler. The fire produces hot combustion gases that travel upwardly through the narrow flues like a chimney. When the escaping heat is sufficient to activate at least one nearby overhead fire sprinkler, water (or other fire suppressing liquid) will be discharged into the region. In order to be effective, the water must travel down the very same flues that the heat from the fire is rising through. The rising heat, concentrated within the narrow passageways of the flues will vaporize the descending water spray unless sufficient quantities of water and/or large enough droplet sizes can be applied to overpower the heat. The greatest success at fire suppression will be achieved when, at the initial stages of a fire, a maximum amount of water is applied to the flues directly above the fire locus.
There is therefore a need in the art for an improved fire suppression system that will produce larger water droplet size and/or increase water discharge velocity, operating with less lines with the possibility of less pressure and volume depending on final storage occupancy. Also, there is a need in the art for a fire suppression system that will deliver the maximum available amounts of water (or other fire suppressing liquid) onto a fire. And still further, there is a need for a fire suppression system that is uniquely designed to combat fires in warehouse settings where storage items are tightly stacked in rows such that water from an activated fire sprinkler must be directed into narrow flues to reach a fire.